"It was unreadable, it was so bad," said Anson Williams, who played Potsie

Three of the original Happy Days castmembers recently reunited to explain just how RobinWilliams got cast as an alien on the comedy series.

"Mork & Mindy was like the worst script in the history of Happy Days. … It was unreadable, it was so bad," said Anson Williams, who played Potsie. He revealed that series creator GarryMarshall had gone to see Star Wars with his son, who asked his father if the show "could do a Martian episode."